Ils nous cherchent au mauvais endroit.
(They are searching for us in the wrong place)
"Ils" is a pronoun meaning "they".
"Nous" is a pronoun meaning "us".
chercher is a verb meaning "to search, to look for". These are present indicative conjugations of chercher:
je cherche (I search...)
tu cherches (you search...)
il/elle cherche (he/she/it searches...)
nous cherchons (we search...)
vous cherchez (you-all search...)
ils/elles cherchent (they search...)
You can see that the conjugation of chercher in the sentence is cherchent (third person plural present indicative).
au is a contraction of "à le". It means "to the / for the / at the".
mauvais means "bad / wrong". Its meaning in the sentence is "wrong".
endroit means "place".